Never save user keys. Make it abundantly clear to them that the keys are not recoverable, and instruct them to create a physical copy of the owner key or master password if you provide one.
Have you checked out hiveinvite? It covers a lot of what you need, is translated in a lot of languages and open source on github.
Oh! If the saving password is what has stopped because I have been told that most people at the beginning can lose their password.
Great, maybe we can work on that, taking part of the Hiveinvite code!
maybe i can write to you